多源信息融合的航空发动机异常检测方法研究

针对航空发动机中单参数表征性能不全面,且易受外部环境和飞行工况等因素影响的问题,提出一种基于谱回归和高斯混合模型的多源信息融合的健康因子构建方法。选取记录完整并与发动机健康性能关系密切的参数,以同架飞机左右发动机的性能参数差异值作为数据源,通过谱回归进行特征降维,采用高斯混合模型构建正常状态模型,再以基于贝叶斯推断的距离表征测试数据与高斯混合模型的全局距离判别发动机的异常状态。通过两个航空发动机异常事件案例中真实QAR数据进行验证,结果表明所提方法相较于航空公司能够更有效评估航空发动机的健康状态,提前识别出发动机的异常点,预留出足够的时间为发动机制定可靠的维修计划,提高飞机的安全性与经济性。     

九头狮子草红色素基膜的制备及动态响应特征

目的 制备了一种九头狮子草红色素基膜,即九头狮子草红色素结合马蹄淀粉的新型比色指示膜。同时利用紫外–可见吸收光谱和灰度平均值探究其动态响应特征。方法 从植物九头狮子草中提取九头狮子草红色素(HPJH),采用共混法将HPJH、马蹄淀粉、丙三醇共混制备比色指示膜。结果 引入九头狮子草红色素后,可以改变马蹄淀粉膜的抗氧化性。适量的九头狮子草红色素促进膜结构的均匀性,当添加质量分数为8%的九头狮子草红色素时,成膜效果最好,DPPH自由基清除率达到88.70%,膜颜色稳定性实验结束时ΔE值为1.649 7。以灰度平均值直观呈现比色指示膜在不同湿度条件下对三乙胺的响应情况,更具有说服力。结论 从植物九头狮子草中提取的HPJH可提高马蹄淀粉膜的指示效果,比色指示膜具有较强的抗氧化性,并对三乙胺具有颜色变化的响应性,在猪肉、鱼肉和莴笋新鲜度监测中具有动态响应特征。     

A numerical algorithm coupling a bifurcating indicator and a direct method for the computation of Hopf bifurcation points in fluid mechanics

This paper deals with the computation of Hopf bifurcation points in fluid mechanics. This computation is done by coupling a bifurcation indicator proposed recently (Cadou et al., 2006) [1] and a direct method (Jackson, 1987; Jepson, 1981) [2] and [3] which consists in solving an augmented system whose solutions are Hopf bifurcation points. The bifurcation indicator gives initial critical values (Reynolds number, Strouhal frequency) for the direct method iterations. Some classical numerical examples from fluid mechanics, in two dimensions, are studied to demonstrate the efficiency and the reliability of such an algorithm.     

基于MSP430的二线制高精度表头设计

针对传统的二线制表头在高温下测量精度差、温漂大的特点,提出了一种在高温下的高精度数显表头的设计方案。分别介绍了其软硬件的实现方法,即采用超低功耗微处理器MSP430F4250采集回路中的电流值,采用24位ADC转换器ADS1244进行模数转换,最后将经过运算的变送器输出信号值在LED数码管中加以显示。实测结果证明,该表头在高温下测量精度高、工作可靠、抗干扰性强、实用性强,势必会成为无源二线制仪表的发展方向。     

Checking determinism of XML Schema content models in optimal time

We consider the determinism checking of XML Schema content models, as required by the W3C Recommendation. We argue that currently applied solutions have flaws and make processors vulnerable to exponential resource needs by pathological schemas, and we help to eliminate this potential vulnerability of XML Schema based systems. XML Schema content models are essentially regular expressions extended with numeric occurrence indicators. A previously published polynomial-time solution to check the determinism of such expressions is improved to run in linear time, and the improved algorithm is implemented and evaluated experimentally. When compared to the corresponding method of a popular production-quality XML Schema processor, the new implementation runs orders of magnitude faster. Enhancing the solution to take further extensions of XML Schema into account without compromising its linear scalability is also discussed.     

电子式车速里程表

详细介绍霍尔速度传感器,里程计数脉冲的产生,步进电机的驱动和ＢＬ２１１５集成电路在电子式车速里程表中的应用。     

水生态文明的内涵及评价体系探讨

阐述了水生态文明的概念和内涵,提出了由两个系统（水生态系统及社会经济系统）、6个对象类型及20个指标共3层构成的水生态文明多层评价指标体系。在评价方法方面,引入了弹性分级评分系统。分级评价标准考虑了我国不同地区的自然和经济社会特点,将水生态文明状况划分为五级,以体现不同地区水生态文明的差异性。     

旱情预警几个主要技术问题的探讨

旱灾是我国主要的自然灾害之一。近年来,我国干旱灾害发生频繁,对经济社会造成的影响不断加剧。加强旱情监测,提高旱情综合评判能力,探索旱情预警方法等,显得十分必要和紧迫。目前,我国旱情监测工作相对薄弱,旱情预测预报起步较晚,旱情预警尚处于研究和探索阶段。本文结合吉林省旱情预警模型研究的有关成果,探讨预警指标、预测模型、预警综合指数等主要技术问题的创建思路,为旱情预警系统研究提供借鉴和参考作用。     

Simulation of thermomechanical behavior during continuous casting process based on MiLE method

A new method called mixed Lagrangian and Eulerian method(MiLE method) was used to simulate the thermomechanical behavior during continuous casting process of steel YF45MnV.The simulation results are basically in agreement with the measured data.The delaying period at the beginning of solidification is about 0.1 in square root of solidification time which is agreement with the data in literatures,and shell thickness increases in linear relation to square root of solidification time.The bloom surface temperature decreases gradually as the casting proceeds.The effective stress in the corner is much larger than that in the mid-face.The corner area is the dangerous zone of cracking.The effects of mold flux break temperature on the air gap and hot tearing indicator were also modeled.The model predicts that the bloom surface temperature increases with the increase of the mold flux break temperature,but the heat flux decreases with the increase of the mold flux break temperature.The hot tearing indicator is much smaller when the mold flux break temperature is higher.     

基于心音的运动员心脏储备评价指标提取方法研究

为提取运动员的心率、第一心音最大幅值(S1)/第二心音最大幅值(S2)和舒张期时限(D)/收缩期时限(S)3项心脏储备评价指标,以评估心脏泵血功能状况,提出了一种心音分析方法。该方法主要包括心音预处理、包络提取、自适应阈值线选取及心音定位4个部分。实验对200例心音信号进行心脏储备评价指标的提取,其结果与其同步的心电信号结果对比发现,该方法的准确率达到96.5%,从而验证了该方法的可行性。最后用该方法提取了30例高水平运动员心脏储备评价指标并进行了评估。其评估结果是29名运动员的3项指标在正常范围内,1例运动员的D/S指标反映出该运动员处在亚健康状态,与实际情况相符。该方法为教练员科学地安排运动员的训练或选拔新的运动人才提供了参考依据。